Process for providing seed layers for integrated circuit metallurgy

ABSTRACT

Structures are provided which improve performance in integrated circuits. The structures include a diffusion barrier and a seed layer in an integrated circuit both formed using a low energy ion implantation followed by a selective deposition of metal lines for the integrated circuit. The low energy ion implantation allows for the distinct placement of both the diffusion barrier and the seed layer. Structures are formed with a barrier/adhesion layer deposited in the number of trenches using a low energy ion implantation, e.g. a 100 to 800 electron volt (eV) ion implantation. A seed layer is deposited on the barrier/adhesion layer in the number of trenches also using the low energy ion implantation. Such structures include aluminum, copper, gold, and silver metal interconnects.

RELATED APPLICATIONS

[0001] This application is a Divisional of U.S. application Ser. No.09/484,002, filed Jan. 18, 2000 which is incorporated herwith.

[0002] This application is related to the following co-pending, commonlyassigned applications: U.S. application Ser. No. 09/128,859 filed Aug.9, 1999, U.S. application Ser. No. 09/488,098, filed Jan. 18, 2000, andU.S. application Ser. No. 09/484,303, filed Jan. 18, 2000, which arehereby incorporated by reference.

FIELD OF THE INVENTION

[0003] The present invention relates generally to integrated circuits.More particularly, it pertains to structures and methods for providingseed layers for integrated circuit metallurgy.

BACKGROUND OF THE INVENTION

[0004] One of the main problems confronting the semiconductor processingindustry, in the ULSI age, is that of Capacitive-Resistance loss in thewiring levels. This has led to a large effort to reduce the resistanceof and lower the capacitive loading on the wiring levels. Since itsbeginning, the industry has relied on aluminum and aluminum alloys forwiring. In a like manner, the industry has mainly relied on SiO₂ as theinsulator of choice, although polyimide was used in a number of productsby one vendor (IBM), for a number of years. The capacitive resistanceproblem grows with each succeeding generation of technology. As thedimensions decrease the minimum line space combination decreases, thusincreasing both capacitance and resistance, if the designer is to takeadvantage of the improved ground rules.

[0005] To improve the conductivity, it has been suggested by numerousinvestigators, that copper or perhaps silver or gold metallurgy besubstituted for the aluminum metallurgy, now being used. Severalpotential problems have been encountered in the development of theseproposed metallurgies. One of the main ones is the fast diffusion ofcopper through both silicon and SiO₂. This along with the known junctionpoising effects of copper and gold have led to proposals to use a liner,to separate these metallurgies from the SiO₂ insulator.

[0006] For example, an article authored by Karen Holloway and Peter M.Fryer, entitled, “Tantalum as a diffusion barrier between copper andsilicon”, Appl. Phys. Letter vol.57, No. 17, Oct. 22, 1990, pp.1736-1738, suggests the use of a tantalum metal liner. In anotherarticle authored by T. Laursen and J. W. Mayer, entitled, “Encapsulationof Copper by Nitridation of Cu-Ti Alloy/Bilayer Structures”,International Conference on Metallurgical Coatings and Thin Films, SanDiego, Calif., Apr. 21-25, 1997, Abstract No. H1.03, pg. 309, suggestsusing a compound such as CuTi as the liner. Still another articlepublished by Vee S. C. Len, R. E. Hurley, N. McCusker, D. W. McNill, B.M. Armstrong and H. S. Gamble, entitled, “An investigation into theperformance of diffusion barrier materials against copper diffusionusing metal-oxide-semiconductor (MOS) capacitor structures”, Solid-StateElectronics 43 (1999) pp. 1045-1049 suggests using a compound such asTaN as the liner. These approaches, however, do not fully resolve theabove-stated problem of the minimum line space decreases. Thus, theshrinking line size in the metal line and liner combination againincreases both the capacitance and resistance.

[0007] At the same time other investigators, in looking at thecapacitive loading effect, have been studying various polymers such asfluorinated polyimides as possible substitutions for SiO₂ insulators.Several of these materials have dielectric constants considerably lowerthan SiO₂. However as in the case of SiO₂, an incompatibility problemwith copper metallurgy has been found. For example, in a presentation byD. J. Godbey, L. J. Buckley, A. P. Purdy and A. W. Snow, entitled,“Copper Diffusion in Organic Polymer Resists and Inter-levelDielectrics”, at the International Conference on Metallurgical Coatingsand Thin Films, San Diego, Calif., Apr. 21-25, 1997, Abstract H2.04 pg.313, it was shown that polyimide, and many other polymers, react withcopper during the curing process, forming a conductive oxide CuO₂, whichis dispersed within the polymer. This then raises the effectivedielectric constant of the polymer and in many cases increases thepolymers conductivity. In addition it has been found that reactive ionetching (RIE) of all three metals, copper, silver or gold, is difficultat best.

[0008] Other approaches by investigators have continued to look for waysto continue to use aluminum wiring with a lower dielectric constantinsulator. This would decrease the capacitive load with a giveninter-line space but require wider or thicker lines. The use of thickerlines would increase the capacitive loading in direct proportion to thethickness increase. Thus to some measure, it defeats the objectives ofdecreasing the capacitive loading effects. Therefore, the use of thickerlines should be avoided as much as possible. As the resistivity of theline is directly proportional to its cross-sectional area, if it cannotbe made thicker, it must be made wider. If however the lines are madewider, fewer wiring channels can be provided in each metal level. Toobtain the same number of wiring channels, additional levels of metalmust be provided. This increases the chip cost. So if this approach isto be followed, it is imperative that a low cost process sequence beadopted.

[0009] One approach provided by the present inventor in a co-pendingapplication, entitled, “Copper Metallurgy in Integrated Circuits”, filedAug. 4, 1998, application Ser. No. 09/128,859, proposes a method tosolve many of the problems associated with using copper in a polymerinsulator. This process, which was specifically designed to becompatible with a polymer or foam insulation, required that the unwantedcopper on the surface of each layer be removed by Chemical MechanicalPolishing (CMP) or a similar planarizing process. However, this methodmay require careful process control, leading to additional expense.Another approach is provided in a co-pending application by Kie Ahn andLeonard Forbes, entitled “Method for Making Copper and Other MetalInterconnections in Integrated Circuits”, filed Feb. 27, 1998, U.S. Ser.No. 09/032,197, which proposes a method using ionized sputtering to formthe underlayer, then forming a low wetting layer on the areas where nocopper is desired using jet vapor deposition. The copper is depositedwith ionized Magnetron sputtering followed by hydrogen annealing. Theexcess copper is then removed by CMP as in the aforementionedapplication.

[0010] Another process is described by the present inventor in aco-pending application, entitled, “Integrated Circuit with OxidationResistant Polymeric Layer”, filed Sep. 1, 1998, U.S. Ser. No.09/145,012, which eliminates many of the CMP processes and uses lift-offto define the trench and the seed layer simultaneously. A process isalso described by the present inventor in a co-pending application,entitled, “Conductive Structures in Integrated Circuits” filed Mar. 1,1999, U.S. Serial No. 09/259,849, which required a CMP process to removeunwanted seed material prior to a selective deposition of the metallayers in a damascene or dual damascene process.

[0011] The use of CMP has proven to be effective in reducing localnon-planarity. However, extensive dishing in wide lines and rounding ofcomers of the insulator are a common occurrence. It has been found thatby maintaining a regular structure through the use of dummy structuresand small feature sizes, it is possible to planarize a level to a nearlyflat surface. The use of these techniques are however costly and in somecases come with density or performance penalties. It is, however,generally possible to planarize a structure prior to the metal levelsusing these methods with little or no density penalty. The use ofelectroless plating has been suggested in an article authored by YosiSchacham-Diamand and Valery M. Dubin, entitled “Copper electrolessdeposition technology for ultra-large scale-integration (ULSI)metallization”, Microelectronic Engineering 33 (1997) 47-58, however asimple process for obtaining both a barrier layer as well as a seedlayer is needed to improve the cost effectiveness of this technique. Onetechnique for seeding polyimide and silicon surfaces using high energy(10-20 Kilo Electron Volts {KEV}) ion implantation has been demonstratedin an article authored by S. Bhansali, D. K. Sood and R. B. Zmood,entitled “Selective electroless copper plating on silicon seeded bycopper ion implantation”, Thin Solid Films V253 (1994) pp. 391-394.However this process has not been shown to be implementable into aproduct structure where a barrier and/or adhesion layer is required.

[0012] For the reasons stated above and for others which will becomeapparent from reading the following disclosure, structures and methodsare needed which alleviate the problems associated with via and metalline fabrication processes. These structures and methods for via andmetal line fabrication must be streamlined and accommodate the demandfor higher performance in integrated circuits even as the fabricationdesign rules shrink.

SUMMARY OF THE INVENTION

[0013] The above mentioned problems associated with integrated circuitsize and performance, the via and metal line formation process, andother problems are addressed by the present invention and will beunderstood by reading and studying the following specification. Thestructures and methods of the present invention include a diffusionbarrier and a seed layer in an integrated circuit both formed using alow energy ion implantation followed by a selective deposition of metallines for the integrated circuit. According to the teachings of thepresent invention, the selective deposition of the metal lines avoidsthe need for multiple chemical mechanical planarization (CMP) steps. Thelow energy ion implantation of the present invention allows for thedistinct placement of both the diffusion barrier and the seed layer. Aresidual resist can be used to remove the diffusion barrier and the seedlayer from unwanted areas on a wafer surface.

[0014] In particular one illustrative embodiment of the presentinvention includes a method of making a diffusion barrier and a seedlayer in an integrated circuit. The method includes patterning aninsulator material to define a number of trenches in the insulator layeropening to a number of first level vias in a planarized surface. Abarrier/adhesion layer is deposited in the number of trenches using alow energy ion implantation, e.g. a 100 to 800 electron volt (eV) ionimplantation. A seed layer is deposited on the barrier/adhesion layer inthe number of trenches also using the low energy ion implantation. Thisnovel methodology further accommodates the formation of aluminum,copper, gold, and/or silver metal interconnects.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following detailed description of the preferred embodimentscan best be understood when read in conjunction with the followingdrawings, in which:

[0016] FIGS. 1A-1K illustrate one embodiment of the various processingsteps for forming vias and metal lines according to the teachings of thepresent invention;

[0017] FIGS. 2A-2K illustrate another embodiment of the variousprocessing steps for forming vias and metal lines according to theteachings of the present invention;

[0018] FIGS. 3A-3K illustrate another embodiment of the variousprocessing steps for forming vias and metal lines according to theteachings of the present invention;

[0019] FIGS. 4A-4L illustrate another embodiment of the variousprocessing steps for forming vias and metal lines according to theteachings of the present invention;

[0020]FIG. 5, is an illustration of an integrated circuit formedaccording to the teachings of the present invention.

[0021]FIG. 6 illustrates an embodiment of a system including a portionof an integrated circuit formed according to any of the embodimentsdescribed in the present application.

DETAILED DESCRIPTION

[0022] In the following detailed description of the invention, referenceis made to the accompanying drawings which form a part hereof, and inwhich is shown, by way of illustration, specific embodiments in whichthe invention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention. Other embodiments may be utilized and structural, logical,and electrical changes may be made without departing from the scope ofthe present invention.

[0023] The terms wafer and substrate used in the following descriptioninclude any structure having an exposed surface with which to form theintegrated circuit (IC) structure of the invention. The term substrateis understood to include semiconductor wafers. The term substrate isalso used to refer to semiconductor structures during processing, andmay include other layers that have been fabricated thereupon. Substrateinclude doped and unhoped semiconductors, epitaxial semiconductor layerssupported by a base semiconductor or insulator, as well as othersemiconductor structures well known to one skilled in the art. The terminsulator is defined to include any material that is less electricallyconductive than the materials generally referred to as conductors bythose skilled in the art. The following detailed description is,therefore, not to be taken in a limiting sense.

[0024] What is disclosed herein is a low cost process to achieve reducedcapacitance and resistance loss in wiring levels. The present inventionrequires only one complete CMP planarizing coupled with the formation ofthe first level vias, no matter how many levels of metallurgy are used.What are essentially cleanup CMP steps on each metal level are used inone process sequence. This process can be used with an aluminum, copper,silver, gold or any other material which can subsequently beelectrolessly plated or deposited by selective CVD or any otherselective deposition process. A polyimide, other polymer or foam polymercan be used as an insulator. It can also be used with an oxide or otherinorganic insulating structure if the insulating stack is compatiblewith the metal being used. It can also be used to form air bridgestructures as well. The process uses low energy ion implantation todeposit both the adhesion and/or barrier layer along with the seedlayer. This is coupled with using the resist layer which defines thedamascene trench as the blocking layer to define the implant areas. Lowenergy implantation allows the placing of distinct layers of bothbarrier/adhesion and seed layers. The use of the same resist layers todefine both the trench and seed layers allows a low cost implementationof the process.

[0025] Embodiment of a Metal Interconnect Using Copper and Polyimide

[0026] FIGS. 1A-1K illustrate a novel methodology for the formation ofmetal interconnects and/or a wiring structure in an integrated circuitaccording to the teachings of the present invention. The novelmethodology includes the novel formation of a barrier/adhesion layer anda seed layer in an integrated circuit using a low energy ionimplantation. The novel methodology also encompasses a novel method ofmaking copper, silver, aluminum, or gold interconnect for an integratedcircuit.

[0027]FIG. 1A illustrates a portion of an integrated circuit structure,namely an integrated circuit having a number of semiconductor devicesformed in a substrate. FIG. 1 illustrates the structure after a devicestructure is formed in the substrate and the contact structure to thedevice structure is in place. One of ordinary skill in the art willunderstand upon reading this disclosure the manner in which a number ofsemiconductor structures, e.g. transistors, can be formed in asubstrate. One of ordinary skill in the art will also understand uponreading this disclosure the manner in which a contact structure can beformed connecting to a given semiconductor device in a substrate. Forexample, FIG. 1A illustrates the structure after a number of devicestructures, e.g. transistor 101A and 101B are formed in the substrate100. An insulator layer 102 is deposited over the number ofsemiconductors 101A and 101B. The deposition of the insulator layer 102can include depositing a layer of Si₃N₄ having a thickness in the rangeof 100 to 500 Angstroms (Å). This insulator layer will also serve as anadditional barrier to impurities coming from subsequent processingsteps. Contact holes 105A and 105B are opened to the number of devicestructures 101A and 101B using a photolithography technique. One ofordinary skill in the are will understand, upon reading this disclosure,the manner in which a photolithography technique can be used to createcontact holes 105A and 105B. In one embodiment of the present inventiona titanium silicide liner 106A and 106B is placed in the contact holes105A and 105B, such a through a process such as chemical vapordeposition (CVD). Next, tungsten vias 107A and 107B can be deposited inthe contact holes 105A and 105B. The tungsten vias 107A and 107B can bedeposited in the contact holes using any suitable technique such asusing a CVD process. The excess tungsten is then removed from the wafersurface by chemical mechanical planarization (CMP) or other suitableprocesses to form a planarized surface 109.

[0028] As shown in FIG. 1B, a first polymer layer 108, or first layer ofpolyimide 108, is deposited over the wafer surface. The first polymerlayer 108 may be deposited using, for example, the process and materialdescribed in co-pending and commonly assigned application U.S. Ser. No.09/128,859, entitled “Copper Metallurgy in Integrated Circuits,” whichis hereby incorporated by reference. In one embodiment, depositing afirst polymer layer 108 includes depositing a foamed polymer layer 108.In one embodiment, the first layer of polyimide 108 is deposited andcured, forming a 5000 Å thick layer of polymer 108 after curing. As oneof ordinary skill in the art will understand, upon reading thisdisclosure, other suitable thickness for the first layer of polyimide108, or insulator layer/material 108, may also be deposited as suitedfor forming a first level metal pattern, the invention is not solimited. The first layer of polyimide 108, or first insulatorlayer/material 108 is patterned to define a number of trenches 110 inthe first insulator layer 108 opening to a number of first level vias,e.g. tungsten vias 107A and 107B in planarized surface 109. In otherwords, a first level metal pattern 110 is defined in a mask layer ofphotoresist 112 and then the first layer of polyimide 108 is etched,using any suitable process, e.g. reactive ion etching (RIE), such thatthe first level metal pattern 110 is defined in the polyimide. Accordingto the teachings of the present invention, a residual photoresist layer112 is left in place on the first insulator layer 108 in a number ofregion 113 outside of the number trenches 110. The structure is now asappears in FIG. 1B.

[0029] As shown in FIG. 1C, a first barrier/adhesion layer 114 isdeposited in the number of trenches 110 using a low energy ionimplantation. In one embodiment according to the teachings of thepresent invention, depositing the barrier/adhesion layer 114 includesdepositing a layer of zirconium 114 having a thickness of approximately5 to 100 Å. In alternate embodiments, depositing the barrier/adhesionlayer 114 includes depositing a barrier/adhesion layer 114 of titaniumand/or hafnium. In one embodiment, depositing the depositing a layer ofzirconium 114 includes depositing a layer of zirconium 114 having athickness of approximately 50 Å. This can be achieved using a 10⁷ ionimplant of zirconium, i.e. 10¹⁷ ions of zirconium per square centimeter(cm²). According to the teachings of the present invention, the layer ofzirconium 114 is implanted at 100 electron volts (eV) into the surfaceof the trenches 110 in the polymer layer 108 using a varying angleimplant (∝), as represented by arrows 111, where the angle ofimplantation is changed from normal to the wafer surface to 15 degreesoff normal. As one of ordinary skill in the art will understand uponreading this disclosure, using a varying angle implant, where an angleof implantation is changed from normal to the planarized surface 109 toapproximately 15 degrees off normal deposits the barrier/adhesion layer114 on all surfaces in the number of trenches 110. The structure is nowas appears in FIG. 1 C.

[0030] In FIG. 1D, a first seed layer 116 is deposited on the firstbarrier/adhesion layer 114 using a low energy ion implantation.According to the broader teachings of the present invention, depositingthe seed layer 116 on the barrier/adhesion layer 114 includes depositinga seed layer 116 selected from the group consisting of aluminum, copper,silver, and gold. However, according to the teachings of the presentembodiment, depositing the seed layer 116 includes depositing a layer ofcopper 116 having a thickness of approximately a 100 Å. This can beachieved using an 8×10¹⁶ ion implant of copper. According to theteachings of the present invention, using a low energy ion implantationincludes implanting the layer of copper 116 at 100 electron volts (eV)into the surface of the trenches 110 in the polymer layer. Also thelayer of copper 116 is implanted at an angle normal to the wafer'ssurface, as shown by arrows 115. As one of ordinary skill in the artwill understand upon reading this disclosure, implanting the layer ofcopper 116 at an angle normal to the planarized surface results in theseed layer of copper 116 remaining on a bottom surface 118 in the numberof trenches 110 and to a much lesser extent on the side surfaces 117 ofthe number of trenches 110. In one embodiment, an optional layer ofaluminum 121 is deposited over the copper seed layer 116 again using alow energy ion implantation of 100 electron volts (eV). The optionallayer of aluminum 121 is deposited to have a thickness of approximatelya 50 Å. This can be achieved using a 3×10⁶ ion implant of aluminumnormal to the wafer surface. As one of ordinary skill in the art willunderstand upon reading this disclosure, the layer of aluminum 121 isused to protect the copper seed layer 116 from oxidation prior tosubsequent processing steps. The structure is now as shown in FIG. 1D.

[0031]FIG. 1E illustrates the structure after the next sequence ofprocess steps. As one of ordinary skill in the art will understand uponreading this disclosure, the residual photoresist layer 112 has servedas a blocking layer to define the implant areas for the barrier/adhesionlayer 114, the seed layer 116, and the layer of aluminum 121. Theresidual photoresist layer 112 is now removed using a wet strip process,as the same will be understood by one of ordinary skill in the art uponreading this disclosure. According to the teachings of the presentinvention, removing the residual photoresist layer 112 includes removingthe unwanted aluminum layer 121, the unwanted seed layer 116, and theunwanted barrier/adhesion layer 114 from other areas of the wafer'ssurface, e.g., from over a number of regions 113 outside of the trenches110 on a top surface 119 of the first insulator layer 108. The structureis now as shown in FIG. 1E.

[0032] In FIG. 1F, a metallic conductor 120, or number of first levelmetal lines 120, is deposited over the seed layer 116 in the number oftrenches 110. According to teachings of the present invention, metallicconductor 120, or number of first level metal lines 120, is selectedfrom the group consisting of aluminum, copper, silver, and golddepending on the type of seed layer 116 which was deposited. Accordingto this embodiment, the metallic conductor 120, or number of first levelmetal lines 120 are selectively formed on the copper seed layer 116 suchthat the number of copper metal lines 120, or first level copper metallines 120 are not formed on the top surface 119 of the first insulatorlayer 108. In one embodiment, the metallic conductor 120, or number offirst level metal lines 120, is deposited using a selective CVD process.In another embodiment, depositing a metallic conductor 120, or number offirst level metal lines 120, over the seed layer 116 includes depositinga metallic conductor 120 using electroless plating. Electroless copperplating is used to deposit sufficient copper to fill the number oftrenches 110 to the top surface 119 of the first insulator layer 108. Asshown in FIG. 1G, the process sequence may be continued to form anynumber of subsequent metal layers in a multilayer wiring structure. FIG.1G illustrates the structure after the next sequence of processingsteps. In FIG. 1G, a dual damascene process is used to define and fill afirst to a second level of vias and a second level metallurgy. To do so,a second polymer layer 124, or second layer of polyimide 124, isdeposited over the wafer surface, e.g. the metallic conductor 120, ornumber of first level metal lines 120, and the first polymer layer 108.The second polymer layer 124 may similarly be deposited using, forexample, the process and material described in co-pending and commonlyassigned application U.S. Ser. No. 09/128,859, entitled “CopperMetallurgy in Integrated Circuits,” which is hereby incorporated byreference. In one embodiment, depositing a second polymer layer 124includes depositing a foamed second polymer layer 124. In oneembodiment, the second polymer layer 124 is deposited and cured, forminga 10,000 Å thick second polymer layer 124 after curing. As one ofordinary skill in the art will understand, upon reading this disclosure,other suitable thickness for the second polymer layer 124, or secondinsulator layer/material 124, may also be deposited as suited forforming a first to a second level of vias, e.g. second level vias, and anumber of second level metal lines, the invention is not so limited. Thesecond polymer layer 124, or second insulator layer/material 124 ispatterned to define a second level of vias and a number of second levelmetal lines in the second insulator layer/material 124 opening to themetallic conductor 120, or number of first level metal lines 120. Inother words, a second level of vias is defined in a second mask layer ofphotoresist 126 and then the second polymer layer 124 is etched, usingany suitable process, e.g. reactive ion etching (RIE), such that asecond level of via openings 128 are defined in the polyimide. Using thedual damascene process, a number of second level metal lines are alsodefined in a second mask layer of photoresist 126 and the second polymerlayer 124 is again etched, using any suitable process, e.g. reactive ionetching (RIE), such that a second level of metal line trenches 130 aredefined in the polyimide. One of ordinary skill in the art willunderstand upon reading this disclosure, the manner in which aphotoresist layer 126 can be mask, exposed, and developed using a dualdamascene process to pattern a second level of via openings 128 and asecond level of metal line trenches 130 in the second insulatorlayer/material 124.

[0033] As described previously, and according to the teachings of thepresent invention, a residual photoresist layer 126 is left in place onthe second insulator layer/material 124 in a number of regions 132outside of the second level of metal line trenches 130. A suitableplasma and/or wet cleaning process is used to remove any contaminatesfrom the second level of via openings 128 and a second level of metalline trenches 130, as the same will be understood by one of ordinaryskill in the art upon reading this disclosure. The structure is now asappears in FIG. 1G.

[0034]FIG. 1H illustrates the structure 100 after the next sequence ofprocessing steps. In FIG. 1H, a second barrier/adhesion layer 134 isdeposited in the second level of via openings 128 and a second level ofmetal line trenches 130 using a low energy ion implantation. Asdescribed above, in one embodiment according to the teachings of thepresent invention, depositing the second barrier/adhesion layer 134includes depositing a layer of zirconium 134 having a thickness ofapproximately 5 to 100 Å. In alternate embodiments, depositing thesecond barrier/adhesion layer 134 includes depositing a barrier/adhesionlayer 134 of titanium and/or hafnium. In one embodiment, depositing thelayer of zirconium 134 includes depositing a layer of zirconium 134having a thickness of approximately 50 Å. In one embodiment, this isachieved using a 10¹⁷ ion implant of zirconium. According to theteachings of the present invention, the layer of zirconium 134 isimplanted at 100 electron volts (eV) into the surface of the secondlevel of via openings 128 and a second level of metal line trenches 130in the second polymer layer 124 using a varying angle, as shown byarrows 125, implant where the angle of implantation is changed fromnormal to the wafer surface to 15 degrees off normal. As one of ordinaryskill in the art will understand upon reading this disclosure, using avarying angle implant, where an angle of implantation is changed fromnormal to the wafer surface to approximately 15 degrees off normaldeposits the barrier/adhesion layer 134 on all surfaces in the secondlevel of via openings 128 and a second level of metal line trenches 130.The structure is now as appears in FIG. 1H.

[0035]FIG. 1H illustrates the structure 100 after the next sequence ofprocessing steps. In FIG. 1H, a second seed layer 136 is deposited onthe second barrier/adhesion layer 134 using a low energy ionimplantation. According to the broader teachings of the presentinvention, depositing the second seed layer 136 on the secondbarrier/adhesion layer 114 includes depositing a second seed layer 136selected from the group consisting of aluminum, copper, silver, andgold. However, according to the teachings of the present embodiment,depositing the second seed layer 136 includes depositing a second layerof copper 136 having a thickness of approximately a 100 Å. In oneembodiment, this is achieved using an 8×10¹⁶ ion implant of copper.According to the teachings of the present invention, using a low energyion implantation includes implanting the layer of copper 136 at 100electron volts (eV) into the surfaces of the second level of viaopenings 128 and the polymer layer. Also the layer of copper 136 isimplanted at an angle normal to the wafer's surface as shown by arrows137. As one of ordinary skill in the art will understand upon readingthis disclosure, implanting the layer of copper 136 at an angle normalto the planarized surface results in the second seed layer of copper 136remaining on a bottom surface 138 in the second level of via openings128 and second level of metal line trenches 130 and to a much lesserextent on the side surfaces 140 of the second level of via openings 128and a second level of metal line trenches 130. In one embodiment, anoptional layer of aluminum 141 is deposited over the second copper seedlayer 136 again using a low energy ion implantation of 100 electronvolts (eV). The optional layer of aluminum is deposited to have athickness of approximately a 50 Å. In one embodiment, this is achievedusing a 3×10¹⁶ ion implant of aluminum normal to the wafer surface. Asone of ordinary skill in the art will understand upon reading thisdisclosure, the layer of aluminum 141 is used to protect the secondcopper seed layer 136 from oxidation prior to subsequent processingsteps.

[0036]FIG. 1J illustrates the structure after the next sequence ofprocessing steps. As one of ordinary skill in the art will understandupon reading this disclosure, the residual photoresist layer 126 hasserved as a blocking layer to define the implant areas for the secondbarrier/adhesion layer 134, the second seed layer 136, and the aluminumlayer 141. The residual photoresist layer 126 is now removed using a wetstrip process, as the same will be understood by one of ordinary skillin the art upon reading this disclosure. According to the teachings ofthe present invention, removing the residual photoresist layer 126includes removing the unwanted aluminum layer 141, the unwanted seedlayer 136, and the unwanted barrier/adhesion layer 134 from other areasof the wafer's surface, e.g. from over a number of regions 132 outsideof second level of metal line trenches 130 on a top surface 142 of thesecond insulator layer 124. The structure is now as shown in FIG. 1J.

[0037] In FIG. 1K, a second metallic conductor 144, or second coreconductor 144, is deposited over or formed on the second seed layer 136and within the second barrier/adhesion layer 134 in the second level ofvia openings 128 and the second level of metal line trenches 130 in thepolymer layer. In this embodiment the second metallic conductor 144, orsecond core conductor 144, is copper, but in other embodiments of thepresent invention can be selected from the group consisting of aluminum,silver, and gold. In one embodiment, the second metallic conductor 144,or second core conductor 144, is deposited using a selective CVD processsuch that the second metallic conductor 144, or second core conductor144 is not formed on a top surface 142 of the second insulator layer124. In another embodiment, depositing a second metallic conductor 144,or second core conductor 144, over on the second seed layer 136 andwithin the second barrier/adhesion layer 134 includes depositing asecond metallic conductor 144, or second core conductor 144, usingelectroless plating. Electroless copper plating is used to depositsufficient copper to fill the second level of via openings 128 and thesecond level of metal line trenches 130 to the top surface 142 of thesecond insulator layer 124. Thus, the second barrier/adhesion layer 134,the second seed layer 136, and the second metallic conductor 144, orsecond core conductor 144, constitute a second number of conductivestructures which includes a number of second level vias and a number ofsecond level metal lines which are formed over and connect to a firstnumber of conductive structures, e.g. the first level metal lines 120.

[0038] Embodiment of a Metal Interconnect Using Aluminum Metal Lines andOxide Insulators

[0039] FIGS. 2A-2K illustrate a novel methodology for the formation ofmetal interconnects and/or a wiring structure in an integrated circuitaccording to the teachings of the present invention. The novelmethodology includes the novel formation of a barrier/adhesion layer anda seed layer in an integrated circuit using a low energy ionimplantation. The novel methodology also encompasses a novel method ofmaking copper, silver, aluminum, or gold interconnect for an integratedcircuit.

[0040]FIG. 2A illustrates a portion of an integrated circuit structure,namely an integrated circuit having a number of semiconductor devicesformed in a substrate as described above in connection with FIG. 1A.That is, FIG. 2A illustrates the structure after a device structure isformed in the substrate and the contact structure to the devicestructure is in place. Like FIG. 1A, FIG. 2A illustrates the structureafter a number of device structures, e.g. transistor 201A and 201B areformed in the substrate 200. An insulator layer 202 is deposited overthe number of semiconductors 201A and 201B. The deposition of theinsulator layer 202 can include depositing a layer of Si₃N₄ having athickness in the range of 100 to 500 Angstroms (Å). This insulator layerwill also serve as an additional barrier to impurities coming fromsubsequent processing steps. Contact holes 205A and 205B are opened tothe number of device structures 201A and 201B using a photolithographytechnique. One of ordinary skill in the are will understand, uponreading this disclosure, the manner in which a photolithographytechnique can be used to create contact holes 205A and 205B. In oneembodiment of the present invention a titanium silicide liner 206A and206B is placed in the contact holes 205A and 205B, such a through aprocess such as chemical vapor deposition (CVD). Next, tungsten vias207A and 207B can be deposited in the contact holes 205A and 205B. Thetungsten vias 207A and 207B can be deposited in the contact holes usingany suitable technique such as using a CVD process. The excess tungstenis then removed from the wafer surface by chemical mechanicalplanarization (CMP) or other suitable processes to form a planarizedsurface 209.

[0041] As shown in FIG. 2B, a first oxide layer 208, e.g. a silicondioxide layer (SiO₂), is deposited over the wafer surface. In oneembodiment, depositing a first oxide layer 208 includes depositing afluorinated silicon oxide layer 208. The first oxide layer 208 may bedeposited using any suitable technique, such as, for example, using aCVD process. In one embodiment, depositing a first oxide layer 208having a thickness of approximately 5000 Å. As one of ordinary skill inthe art will understand, upon reading this disclosure, other suitablethicknesses for the first oxide layer 208 may also be deposited assuited for forming a first level metal pattern, the invention is not solimited. The first oxide layer 208 is patterned to define a number oftrenches 210 in the first oxide layer 208 opening to a number of firstlevel vias, e.g. tungsten vias 207A and 207B in planarized surface 209.In other words, a first level metal pattern 210 is defined in a masklayer of photoresist 212 and then the first oxide layer 208 is etched,using any suitable process, e.g. reactive ion etching (RIE), such thatthe first level metal pattern 210 is defined in the first oxide layer208. One of ordinary skill in the art will understand upon reading thisdisclosure that any desired first level metal pattern 210 can be createdusing a photolithography technique. According to the teachings of thepresent invention, a residual photoresist layer 212 is left in place onthe first oxide layer 208 in a number of region 213 outside of thenumber trenches 210. The structure is now as appears in FIG. 2B.

[0042] As shown in FIG. 2C, a first barrier/adhesion layer 214 isdeposited in the number of trenches 210 using a low energy ionimplantation. In one embodiment according to the teachings of thepresent invention, depositing the barrier/adhesion layer 214 includesdepositing a layer of zirconium 214 having a thickness of approximately5 to 100 Å. In alternate embodiments, depositing the barrier/adhesionlayer 214 includes depositing a barrier/adhesion layer 214 of titaniumand/or hafnium. In one embodiment, depositing the depositing a layer ofzirconium 214 includes depositing a layer of zirconium 214 having athickness of approximately 50 Å. This can be achieved using a 10¹⁷ ionimplant of zirconium. According to the teachings of the presentinvention, the layer of zirconium 214 is implanted at 100 electron volts(eV) into the surface of the trenches 210 in the first oxide layer 208using a varying angle implant (∝), as represented by arrows 211, wherethe angle of implantation is changed from normal to the wafer surface to15 degrees off normal. As one of ordinary skill in the art willunderstand upon reading this disclosure, using a varying angle implant,where an angle of implantation (∝) is changed from normal to the wafer'ssurface to approximately 15 degrees off normal deposits thebarrier/adhesion layer 214 on all surfaces in the number of trenches210. The structure is now as appears in FIG. 2C.

[0043] In FIG. 2D, a first seed layer 216 is deposited on the firstbarrier/adhesion layer 214 using a low energy ion implantation.According to the broader teachings of the present invention, depositingthe seed layer 216 on the barrier/adhesion layer 214 includes depositinga first seed layer 216 selected from the group consisting of aluminum,copper, silver, and gold. However, according to the teachings of thepresent embodiment, depositing the seed layer 216 includes depositing alayer of an aluminum copper alloy 216 having a thickness ofapproximately 110 Å. This can be achieved by depositing a first layer ofaluminum 281 on the barrier/adhesion layer 214 to a thickness ofapproximately 50 Å using a low energy ion implantation of approximately100 electron volts (eV). A layer of copper 282 is then deposited on thefirst layer of aluminum 281 to a thickness of approximately 10 Å using alow energy ion implantation of approximately 100 eV. A second layer ofaluminum 283 is then deposited on the layer of copper 282 to a thicknessof approximately 50 Å using a low energy ion implantation ofapproximately 100 eV. Also the first seed layer 216 is implanted at anangle normal to the planarized surface, as shown by arrows 215. As oneof ordinary skill in the art will understand upon reading thisdisclosure, implanting the first seed layer 216 at an angle normal tothe planarized surface results in the first seed layer 216 remaining ona bottom surface 218 in the number of trenches 210 and to a much lesserextent on the side surfaces 217 of the number of trenches 210.

[0044]FIG. 2E illustrates the structure after the next sequence ofprocessing steps. As one of ordinary skill in the art will understandupon reading this disclosure, the residual photoresist layer 212 hasserved as a blocking layer to define the implant areas for thebarrier/adhesion layer 214 and the seed layer 216. The residualphotoresist layer 212 is now removed using a wet strip process, as thesame will be understood by one of ordinary skill in the art upon readingthis disclosure. According to the teachings of the present invention,removing the residual photoresist layer 212 includes removing theunwanted seed layer 216 and the unwanted barrier/adhesion layer 214 fromother areas of the wafer's surface, e.g. from over a number of regions213 outside of the trenches 210 on a top surface 219 of the firstinsulator layer 208. The structure is now as shown in FIG. 2E.

[0045] In FIG. 2F, a metallic conductor 220, or number of first levelmetal lines 220, is deposited over the first seed layer 216 and withinthe first barrier/adhesion layer 214 in the number of trenches 210. Inthis embodiment, the metallic conductor 220, or number of first levelmetal lines 220, is aluminum, but in other embodiments of the presentinvention the metallic conductor 220, or number of first level metallines 220, is selected from the group consisting of copper, silver, andgold depending on the type of seed layer 216 which was deposited. In oneembodiment, the metallic conductor 220, or number of first level metallines 220, is deposited using a selective CVD process. In anotherembodiment, depositing a metallic conductor 220, or number of firstlevel metal lines 220, over the seed layer 216 includes depositing ametallic conductor 220 using electroless plating. According to theteachings of the present invention the number of first level aluminummetal lines 220, is deposited to fill the number of trenches 210 to thetop surface 219 of the first oxide layer 208. Thus, the first levelaluminum metal lines 220, the first seed layer 216, and the firstbarrier/adhesion layer 214 in the number of trenches 210 constitute afirst number of conductive structures. The copper composition of thefirst seed layer 216 can be adjusted to give the appropriate percentageof copper in the completed first number of conductive structures. Forexample, in the above described embodiment the layer thicknesses of thealuminum copper sandwich was designed to give a 0.7 weight percent ofcopper in the first number of conductive structures.

[0046] As shown in FIG. 2G, the process sequence may be continued toform any number of subsequent metal layers in a multilayer wiringstructure. FIG. 2G illustrates the structure after the next sequence ofprocessing steps. In FIG. 2G, a dual damascene process is used to defineand fill a first to a second level of vias and a second levelmetallurgy. To do so, a second oxide layer 224 is deposited over thewafer surface, e.g. the metallic conductor 220, or number of first levelmetal lines 220, and the first oxide layer 208. In one embodiment,depositing a second oxide layer 224 includes depositing a secondfluorinated silicon oxide layer 224. In one embodiment, the second oxidelayer 224 is formed to have a thickness of approximately 10,000 Å. Asone of ordinary skill in the art will understand, upon reading thisdisclosure, other suitable thickness for the second oxide layer 224 mayalso be deposited as suited for forming a first to a second level ofvias, e.g. second level vias, and a number of second level metal lines,the invention is not so limited. The second oxide layer 224 is patternedto define a second level of vias and a number of second level metallines in the second oxide layer 224 opening to the metallic conductor220, or number of first level metal lines 220. In other words, a secondlevel of vias is defined in a second mask layer of photoresist 226 andthen the second oxide layer 224 is etched, using any suitable process,e.g. reactive ion etching (RIE), such that a second level of viaopenings 228 are defined in the polyimide. Using the dual damasceneprocess, a number of second level metal lines are also defined in asecond mask layer of photoresist 226 and the second oxide layer 224 isagain etched, using any suitable process, e.g. reactive ion etching(RIE), such that a second level of metal line trenches 230 are definedin the second oxide layer 224. One of ordinary skill in the art willunderstand upon reading this disclosure, the manner in which aphotoresist layer 226 can be mask, exposed, and developed using a dualdamascene process to pattern a second level of via openings 228 and asecond level of metal line trenches 230 in the second oxide layer 224.

[0047] As described previously, and according to the teachings of thepresent invention, a residual photoresist layer 226 is left in place onthe second oxide layer 224 in a number of regions 232 outside of thesecond level of metal line trenches 230. A suitable plasma and/or wetcleaning process is used to remove any contaminates from the secondlevel of via openings 228 and a second level of metal line trenches 230,as the same will be understood by one of ordinary skill in the art uponreading this disclosure. The structure is now as appears in FIG. 2G.

[0048]FIG. 2H illustrates the structure after the next sequence ofprocessing steps. In FIG. 2H, a second barrier/adhesion layer 234 isdeposited in the second level of via openings 228 and a second level ofmetal line trenches 230 using a low energy ion implantation. Asdescribed above, in one embodiment according to the teachings of thepresent invention, depositing the second barrier/adhesion layer 234includes depositing a layer of zirconium 234 having a thickness ofapproximately 5 to 100 Å. In alternate embodiments, depositing thesecond barrier/adhesion layer 234 includes depositing a barrier/adhesionlayer 234 of titanium and/or hafnium. In one embodiment, depositing thelayer of zirconium 234 includes depositing a layer of zirconium 234having a thickness of approximately 50 Å. In one embodiment, this isachieved using a 10¹⁷ ion implant of zirconium (that is 10¹⁷ ions persquare centimeter). According to the teachings of the present invention,the layer of zirconium 234 is implanted at 100 electron volts (eV) intothe surface of the second level of via openings 228 and a second levelof metal line trenches 230 in the second polymer layer 224 using avarying angle implant (∝), as shown by arrows 225 where the angle ofimplantation is changed from normal to the wafer surface to 15 degreesoff normal. As one of ordinary skill in the art will understand uponreading this disclosure, using a varying angle implant, where an angleof implantation, ∝, is changed from normal to the wafer surface toapproximately 15 degrees off normal deposits the barrier/adhesion layer234 on all surfaces in the second level of via openings 228 and a secondlevel of metal line trenches 230. The structure is now as appears inFIG. 2H.

[0049]FIG. 2I illustrates the structure after the next sequence ofprocessing steps. In FIG. 2I, a second seed layer 236 is deposited onthe second barrier/adhesion layer 234 using a low energy ionimplantation. According to the broader teachings of the presentinvention, depositing the second seed layer 236 on the secondbarrier/adhesion layer 214 includes depositing a second seed layer 236selected from the group consisting of aluminum, copper, silver, andgold. However, according to the teachings of the present embodiment,depositing the seed layer 216 includes depositing a layer of an aluminumcopper alloy 216 having a thickness of approximately 110 Å. This can beachieved by depositing a first layer of aluminum 284 on thebarrier/adhesion layer 214 to a thickness of approximately 50 Å using alow energy ion implantation of approximately 100 electron volts (eV). Alayer of copper 285 is then deposited on the first layer of aluminum 284to a thickness of approximately 10 Å using a low energy ion implantationof approximately 100 eV. A second layer of aluminum 286 is thendeposited on the layer of copper 285 to a thickness of approximately 50Å using a low energy ion implantation of approximately 100 eV. Also thefirst seed layer 216 is implanted at an angle normal to the wafer'ssurface as shown by arrows 237. As one of ordinary skill in the art willunderstand upon reading this disclosure, implanting the layer of copper236 at an angle normal to the planarized surface results in the secondseed layer of copper 236 remaining on a bottom surface 238 in the secondlevel of via openings 228 and to a much lesser extent on the sidesurfaces 240 of the second level of via openings 228 and a second levelof metal line trenches 230.

[0050]FIG. 2J illustrates the structure following the next sequence ofprocess steps. As one of ordinary skill in the art will understand uponreading this disclosure, the residual photoresist layer 226 has servedas a blocking layer to define the implant areas for the secondbarrier/adhesion layer 234 and the second seed layer 236. The residualphotoresist layer 226 is now removed using a wet strip process, as thesame will be understood by one of ordinary skill in the art upon readingthis disclosure. According to the teachings of the present invention,removing the residual photoresist layer 226 includes removing theunwanted barrier/adhesion layer 234 and the unwanted second seed layer236, from other areas of the wafer's surface, e.g. from over a number ofregions 232 outside of second level of metal line trenches 230 on a topsurface 242 of the second oxide layer 224. The structure is now as shownin FIG. 2J.

[0051] In FIG. 2K, a second metallic conductor 244, or second coreconductor 244, is deposited over or formed on the second seed layer 236and within the second barrier/adhesion layer 234 in the second level ofvia openings 228 and the second level of metal line trenches 230 in thepolymer layer. In this embodiment the second metallic conductor 244, orsecond core conductor 244, is aluminum, but in other embodiments of thepresent invention the second metallic conductor 244, or second coreconductor 244, can be selected from the group consisting of copper,silver, and gold. In one embodiment, the second metallic conductor 244,or second core conductor 244, is deposited using a selective CVDprocess. In another embodiment, depositing a second metallic conductor244, or second core conductor 244, over on the second seed layer 236 andwithin the second barrier/adhesion layer 234 includes depositing asecond metallic conductor 244, or second core conductor 244, usingelectroless plating. The second aluminum conductor 244, or second coreconductor 244 is deposited to fill the second level of via openings 228and the second level of metal line trenches 230 to the top surface 242of the second insulator layer 224. Thus, the second barrier/adhesionlayer 234, the second seed layer 236, and the second metallic conductor244, or second core conductor 244, constitute a second number ofconductive structures which includes a number of second level vias and anumber of second level metal lines which are formed over and connect toa first number of conductive structures, e.g. the first level of vias207A and 207B.

[0052] Embodiment of a Metal Interconnect Using Copper Metal Lines andOxide Insulators

[0053] FIGS. 3A-3K illustrate a novel methodology for the formation ofmetal interconnects and/or a wiring structure in an integrated circuitaccording to the teachings of the present invention. The novelmethodology includes the novel formation of a barrier/adhesion layer anda seed layer in an integrated circuit using a low energy ionimplantation. The novel methodology also encompasses a novel method ofmaking copper, silver, aluminum, or gold interconnect for an integratedcircuit.

[0054]FIG. 3A illustrates a portion of an integrated circuit structure,namely an integrated circuit having a number of semiconductor devicesformed in a substrate. FIG. 3 illustrates the structure after a devicestructure is formed in the substrate and the contact structure to thedevice structure is in place. One of ordinary skill in the art willunderstand upon reading this disclosure the manner in which a number ofsemiconductor structures, e.g. transistors, can be formed in asubstrate. One of ordinary skill in the art will also understand uponreading this disclosure the manner in which a contact structure can beformed connecting to a given semiconductor device in a substrate, suchas explained in connection with FIG. 1A. For example, FIG. 3Aillustrates the structure after a number of device structures, e.g.transistor 301A and 301B are formed in the substrate 300. An insulatorlayer 302 is deposited over the number of semiconductors 301A and 301B.The deposition of the insulator layer 302 can include depositing a layerof Si₃N₄ having a thickness in the range of 100 to 500 Angstroms (Å).This insulator layer will also serve as an additional barrier toimpurities coming from subsequent processing steps. Contact holes 305Aand 305B are opened to the number of device structures 301A and 301Busing a photolithography technique. One of ordinary skill in the arewill understand, upon reading this disclosure, the manner in which aphotolithography technique can be used to create contact holes 305A and305B. In one embodiment of the present invention a titanium silicideliner 306A and 306B is placed in the contact holes 305A and 305B, such athrough a process such as chemical vapor deposition (CVD). Next,tungsten vias 306A and 306B can be deposited in the contact holes 305Aand 305B. The tungsten vias 307A and 307B can be deposited in thecontact holes using any suitable technique such as using a CVD process.The excess tungsten is then removed from the wafer surface by chemicalmechanical planarization (CMP) or other suitable processes to form aplanarized surface 309.

[0055] As shown in FIG. 3B, a first polymer layer 308, or first layer ofpolyimide 308, is deposited over the wafer surface. The first oxidelayer 308 may be deposited using any suitable technique such as, forexample, a CVD process. In one embodiment, depositing a first oxidelayer 308 includes depositing a fluorinated silicon oxide layer 308. Inone embodiment, the first oxide layer 308 is deposited to have athickness of approximately 5000 Å. As one of ordinary skill in the artwill understand, upon reading this disclosure, other suitable thicknessfor the first oxide layer 308 may also be deposited as suited forforming a first level metal pattern, the invention is not so limited.The first oxide layer 308 is patterned to define a number of trenches310 in the first oxide layer 308 opening to a number of first levelvias, e.g. tungsten vias 307A and 307B in planarized surface 309. Inother words, a first level metal pattern 310 is defined in a mask layerof photoresist 312 and then the first oxide layer 308 is etched, usingany suitable process, e.g. reactive ion etching (RIE), such that thefirst level metal pattern 310 is defined in the first oxide layer 308.According to the teachings of the present invention, a residualphotoresist layer 312 is left in place on the first oxide layer 308 in anumber of region 313 outside of the number trenches 310. The structureis now as appears in FIG. 3B.

[0056] As shown in FIG. 3C, a first barrier/adhesion layer 314 isdeposited in the number of trenches 310 using a low energy ionimplantation. In one embodiment according to the teachings of thepresent invention, depositing the barrier/adhesion layer 314 includesdepositing a tantalum nitride layer 314 having a thickness ofapproximately 5 to 100 Å. In alternate embodiments, depositing thebarrier/adhesion layer 314 includes depositing a barrier/adhesion layer314 of tantalum and/or CuTi. In one embodiment, depositing the tantalumnitride layer 314 includes first depositing a layer of tantalum 381 tohave a thickness of approximately 100 Å using a low energy ionimplantation of approximately 100 electron volts (eV) at a varying angleimplant (∝), e.g. the angle of implantation (∝) is changed from normalto the planarized surface 309 to approximately 15 degrees off normal asshown by arrows 311. In one embodiment, this is achieved using a 10¹⁷ion implant of tantalum. Next, according to the teachings of the presentinvention, a layer of nitrogen 382 is implanted at 700 electron volts(eV) into the layer of tantalum 381. In one embodiment, this is achievedusing an 8×10¹⁶ ion implant of nitrogen. As one of ordinary skill in theart will understand upon reading this disclosure, using a varying angleimplant, where an angle of implantation is changed from normal to theplanarized surface 309 to approximately 15 degrees off normal depositsthe barrier/adhesion layer 314 on all surfaces in the number of trenches310. The structure is now as appears in FIG. 3C.

[0057] In FIG. 3D, a first seed layer 316 is deposited on the firstbarrier/adhesion layer 314 using a low energy ion implantation.According to the broader teachings of the present invention, depositingthe seed layer 316 on the barrier/adhesion layer 314 includes depositinga seed layer 316 selected from the group consisting of aluminum, copper,silver, and gold. However, according to the teachings of the presentembodiment, depositing the seed layer 316 includes depositing a layer ofcopper 316 having a thickness of approximately 50 Å. This can beachieved using an 8×10¹⁶ ion implant of copper. According to theteachings of the present invention, using a low energy ion implantationincludes implanting the layer of copper 316 at 100 electron volts (eV)into the first barrier/adhesion layer 314. Also the layer of copper 316is implanted at an angle normal to the planarized surface 309 as shownby arrows 315. As one of ordinary skill in the art will understand uponreading this disclosure, implanting the layer of copper 316 at an anglenormal to the planarized surface results in the seed layer of copper 316remaining on a bottom surface 318 in the number of trenches 310 and to amuch lesser extent on the side surfaces 320 of the number of trenches310. In one embodiment, an optional layer of aluminum 321 is depositedover the copper seed layer 316 again using a low energy ion implantationof 100 electron volts (eV). The optional layer of aluminum 321 isdeposited to have a thickness of approximately a 50 Å. This can beachieved using a 3×10¹⁶ ion implant of aluminum normal to the wafersurface. As one of ordinary skill in the art will understand uponreading this disclosure, the layer of aluminum 321 is used to protectthe copper seed layer 316 from oxidation prior to subsequent processingsteps. The structure is now as appears in FIG. 3D.

[0058]FIG. 3E illustrates the structure after the next sequence ofprocessing steps. As one of ordinary skill in the art will understandupon reading this disclosure, the residual photoresist layer 312 hasserved as a blocking layer to define the implant areas for thebarrier/adhesion layer 314, the seed layer 316, and the layer ofaluminum 321. The residual photoresist layer 312 is now removed using awet strip process, as the same will be understood by one of ordinaryskill in the art upon reading this disclosure. According to theteachings of the present invention, removing the residual photoresistlayer 312 includes removing the unwanted aluminum layer 321, theunwanted seed layer 316, and the unwanted barrier/adhesion layer 314from other areas of the wafer's surface, e.g. from over a number ofregions outside of the trenches 310 on a top surface 319 of the firstinsulator layer 308. The structure is now as shown in FIG. 3E.

[0059] In FIG. 3F, a metallic conductor 320, or number of first levelmetal lines 320, is deposited over the seed layer 316 in the number oftrenches 310. According to teachings of the present embodiment, themetallic conductor 320, or number of first level metal lines 320, iscopper. In one embodiment, the metallic conductor 320, or number offirst level metal lines 320, is deposited using a selective CVD process.In another embodiment, depositing a metallic conductor 320, or number offirst level metal lines 320, over the seed layer 316 includes depositinga metallic conductor 320 using electroless plating. Electroless copperplating is used to deposit sufficient copper to fill the number oftrenches 310 to a level approximately 100 Å below the top surface 319 ofthe first oxide layer 308. At this point, a second layer of tantalumnitride 323 is deposited to a thickness of approximately 100 Å on thecopper metallic conductor 320, or number of first level copper lines320. A chemical mechanical planarization (CMP) cleanup process is thenused to remove the tantalum nitride from the top surface 319 of thefirst oxide layer 308.

[0060] As shown in FIG. 3G, the process sequence may be continued toform any number of subsequent metal layers in a multilayer wiringstructure. FIG. 3G illustrates the structure after the next sequence ofprocessing steps. In FIG. 3G, a dual damascene process is used to defineand fill a first to a second level of vias and a second levelmetallurgy. To do so, a second oxide layer 324 is deposited over thewafer surface, e.g. the metallic conductor 320, or number of first levelmetal lines 320, and the first oxide layer 308. The second oxide layer324 is again deposited using any suitable technique. In one embodiment,depositing a second oxide layer 324 includes depositing a fluorinatedsilicon oxide layer 324. In one embodiment, the second oxide layer 324is deposited to have a thickness of approximately 10,000 Å. As one ofordinary skill in the art will understand, upon reading this disclosure,other suitable thickness for the second oxide layer 324 may also bedeposited as suited for forming a first to a second level of vias, e.g.second level vias, and a number of second level metal lines, theinvention is not so limited. The second oxide layer 324 is patterned todefine a second level of vias and a number of second level metal linesin the second oxide layer 324 opening to the metallic conductor 320, ornumber of first level metal lines 320. In other words, a second level ofvias is defined in a second mask layer of photoresist 326 and then thesecond oxide layer 324 is etched, using any suitable process, e.g.reactive ion etching (RIE), such that a second level of via openings 328are defined in the second oxide layer 324. Using the dual damasceneprocess, a number of second level metal lines are also defined in asecond mask layer of photoresist 326 and the second oxide layer 324 isagain etched, using any suitable process, e.g. reactive ion etching(RIE), such that a second level of metal line trenches 330 are definedin the oxide. One of ordinary skill in the art will understand uponreading this disclosure, the manner in which a photoresist layer 326 canbe mask, exposed, and developed using a dual damascene process topattern a second level of via openings 328 and a second level of metalline trenches 330 in the second oxide layer 324.

[0061] As described previously, and according to the teachings of thepresent invention, a residual photoresist layer 326 is left in place onthe second oxide layer 324 in a number of regions 332 outside of thesecond level of metal line trenches 330. A suitable plasma and/or wetcleaning process is used to remove any contaminates from the secondlevel of via openings 328 and a second level of metal line trenches 330,as the same will be understood by one of ordinary skill in the art uponreading this disclosure. The structure is now as appears in FIG. 3G.

[0062]FIG. 3H illustrates the structure after the next sequence ofprocessing steps. In FIG. 3H, a second barrier/adhesion layer 334 isdeposited in the second level of via openings 328 and a second level ofmetal line trenches 330 using a low energy ion implantation. Asdescribed above, in one embodiment according to the teachings of thepresent invention, depositing the second barrier/adhesion layer 334includes depositing a tantalum nitride layer 334 having a thickness ofapproximately 5 to 100 Å. In alternate embodiments, depositing thesecond barrier/adhesion layer 334 includes depositing a secondbarrier/adhesion layer 334 of tantalum and/or CuTi. In one embodiment,depositing the tantalum nitride layer 334 includes first depositing alayer of tantalum 383 to have a thickness of approximately 100 Å using alow energy ion implantation of approximately 100 electron volts (eV) ata varying angle implant (∝), e.g. the angle of implantation (∝) ischanged from normal to the wafer's surface to approximately 15 degreesoff normal as shown by arrows 325. In one embodiment, this is achievedusing a 10¹⁷ ion implant of tantalum. Next, according to the teachingsof the present invention, a layer of nitrogen 384 is implanted at 700electron volts (eV) into the layer of tantalum 383. In one embodiment,this is achieved using an 8×10¹⁶ ion implant of nitrogen. As one ofordinary skill in the art will understand upon reading this disclosure,using a varying angle implant (∝), where an angle of implantation ischanged from normal to the wafer's surface to approximately 15 degreesoff normal deposits the second barrier/adhesion layer 334 on allsurfaces in the second level of via openings 328 and in the second levelof metal line trenches 330 formed in the second oxide layer 324. Thestructure is now as appears in FIG. 3H.

[0063]FIG. 3I illustrates the structure after the next sequence ofprocessing steps. In FIG. 3I, a second seed layer 336 is deposited onthe second barrier/adhesion layer 334 using a low energy ionimplantation. According to the broader teachings of the presentinvention, depositing the second seed layer 336 on the secondbarrier/adhesion layer 314 includes depositing a second seed layer 336selected from the group consisting of aluminum, copper, silver, andgold. However, according to the teachings of the present embodiment,depositing the second seed layer 336 includes depositing a second layerof copper 336 having a thickness of approximately 50 Å. In oneembodiment, this is achieved using an 8×10¹⁶ ion implant of copper.According to the teachings of the present invention, using a low energyion implantation includes implanting the layer of copper 336 at 100electron volts (eV) into the surfaces of the second level of viaopenings 328 and the second level of metal line trenches 330 in thepolymer layer. Also the layer of copper 336 is implanted at an anglenormal to the wafer's surface as shown by arrows 337. As one of ordinaryskill in the art will understand upon reading this disclosure,implanting the layer of copper 336 at an angle normal to the wafer'ssurface results in the second seed layer of copper 336 remaining on abottom surface 338 in the second level of via openings 328 and to a muchlesser extent on the side surfaces 340 of the second level of viaopenings 328 and a second level of metal line trenches 330. In oneembodiment, an optional layer of aluminum 341 is deposited over thesecond copper seed layer 336 again using a low energy ion implantationof 100 electron volts (eV). The optional layer of aluminum is depositedto have a thickness of approximately a 50 Å. In one embodiment, this isachieved using a 3×10¹⁶ ion implant of aluminum normal to the wafersurface. As one of ordinary skill in the art will understand uponreading this disclosure, the layer of aluminum 341 is used to protectthe second copper seed layer 336 from oxidation prior to subsequentprocessing steps. The structure is now as shown in FIG. 3I.

[0064]FIG. 3J illustrates the structure after the next sequence ofprocessing steps. As one of ordinary skill in the art will understandupon reading this disclosure, the residual photoresist layer 326 hasserved as a blocking layer to define the implant areas for the secondbarrier/adhesion layer 334, the second seed layer 336, and the aluminumlayer 341. The residual photoresist layer 326 is now removed using a wetstrip process, as the same will be understood by one of ordinary skillin the art upon reading this disclosure. According to the teachings ofthe present invention, removing the residual photoresist layer 326includes removing the unwanted aluminum layer 341, the unwanted seedlayer 336, and the unwanted barrier/adhesion layer 334 from other areasof the wafer's surface, e.g. from over a number of regions 332 outsideof second level of metal line trenches 330 on a top surface 342 of thesecond insulator layer 324. The structure is now as shown in FIG. 3J.

[0065] In FIG. 3K, a second metallic conductor 344, or second coreconductor 344, is deposited over or formed on the second seed layer 336and within the second barrier/adhesion layer 334 in the second level ofvia openings 328 and the second level of metal line trenches 330 in thepolymer layer. In this embodiment the second metallic conductor 344, orsecond core conductor 344, is copper, but in other embodiments of thepresent invention the second metallic conductor 344, or second coreconductor 344, can be selected from the group consisting of aluminum,silver, and gold. In one embodiment, the second metallic conductor 344,or second core conductor 344, is deposited using a selective CVDprocess. In another embodiment, depositing a second metallic conductor344, or second core conductor 344, over on the second seed layer 336 andwithin the second barrier/adhesion layer 334 includes depositing asecond metallic conductor 344, or second core conductor 344, usingelectroless plating. Electroless copper plating is used to depositsufficient copper to fill the second level of via openings 328 and thesecond level of metal line trenches 330 to level approximately 100 Åbelow the top surface 342 of the second insulator layer 324. At thispoint, a second layer of tantalum nitride 346 is deposited to athickness of approximately 100 Å on the second metallic conductor 344,or second core conductor 344. A chemical mechanical planarization (CMP)cleanup process is then used to remove the tantalum nitride from the topsurface 342 of the second insulator layer 324. Thus, the secondbarrier/adhesion layer 334, the second seed layer 336, and the secondmetallic conductor 344, or second core conductor 344, constitute asecond number of conductive structures which includes a number of secondlevel vias and a number of second level metal lines which are formedover and connect to a first number of conductive structures, e.g. themetallic conductor 320, or number of first level metal lines 320.

[0066] Another Embodiment of a Metal Interconnect Using Copper

[0067] FIGS. 4A-4L illustrate a novel methodology for the formation ofmetal interconnects and/or a wiring structure in an integrated circuitaccording to the teachings of the present invention. The novelmethodology includes the novel formation of a barrier/adhesion layer anda seed layer in an integrated circuit using a low energy ionimplantation. The novel methodology also encompasses a novel method ofmaking copper, silver, aluminum, or gold interconnect for an integratedcircuit.

[0068]FIG. 4A illustrates a portion of an integrated circuit structure,namely an integrated circuit having a number of semiconductor devicesformed in a substrate. FIG. 4A illustrates the structure after a devicestructure is formed in the substrate and the contact structure to thedevice structure is in place. One of ordinary skill in the art willunderstand upon reading this disclosure the manner in which a number ofsemiconductor structures, e.g. transistors, can be formed in asubstrate. One of ordinary skill in the art will also understand uponreading this disclosure the manner in which a contact structure can beformed connecting to a given semiconductor device in a substrate, suchas described in connection with FIG. 1A. For example, FIG. 4Aillustrates the structure after a number of device structures, e.g.transistor 401A and 401B are formed in the substrate 400. An insulatorlayer 402 is deposited over the number of semiconductors 401A and 401B.The deposition of the insulator layer 402 can include depositing a layerof Si₃N₄ having a thickness in the range of 100 to 500 Angstroms (Å).This insulator layer will also serve as an additional barrier toimpurities coming from subsequent processing steps. Contact holes 405Aand 405B are opened to the number of device structures 401A and 401Busing a photolithography technique. One of ordinary skill in the arewill understand, upon reading this disclosure, the manner in which aphotolithography technique can be used to create contact holes 405A and405B. In one embodiment of the present invention a titanium silicideliner 406A and 406B is placed in the contact holes 405A and 405B, such athrough a process such as chemical vapor deposition (CVD). Next,tungsten vias 407A and 407B can be deposited in the contact holes 405Aand 405B. The tungsten vias 407A and 407B can be deposited in thecontact holes using any suitable technique such as using a CVD process.The excess tungsten is then removed from the wafer surface by chemicalmechanical planarization (CMP) or other suitable processes to form aplanarized surface 409.

[0069] As shown in FIG. 4B, a first polymer layer 408, or first layer ofpolyimide 408, is deposited over the wafer surface. The first polymerlayer 408 may be deposited using, for example, the process and materialdescribed in co-pending and commonly assigned application U.S. Ser. No.09/128,859, entitled “Copper Metallurgy in Integrated Circuits,” whichis hereby incorporated by reference. In one embodiment, depositing afirst polymer layer 408 includes depositing a foamed polymer layer 408.In one embodiment, the first layer of polyimide 408 is deposited andcured, forming a 5000 Å thick layer of polymer 408 after curing. As oneof ordinary skill in the art will understand, upon reading thisdisclosure, other suitable thickness for the first layer of polyimide408, or insulator layer/material 408, may also be deposited as suitedfor forming a first level metal pattern, the invention is not solimited. The first layer of polyimide 408, or first insulatorlayer/material 408 is patterned to define a number of trenches 410 inthe first insulator layer 408 opening to a number of first level vias,e.g. tungsten vias 407A and 407B in planarized surface 409. In otherwords, a first level metal pattern 410 is defined in a mask layer ofphotoresist 412 and then the first layer of polyimide 408 is etched,using any suitable process, e.g. reactive ion etching (RIE), such thatthe first level metal pattern 410 is defined in the polyimide. Accordingto the teachings of the present invention, a residual photoresist layer412 is left in place on the first insulator layer 408 in a number ofregion 413 outside of the number trenches 410. The structure is now asappears in FIG. 4B.

[0070] As shown in FIG. 4C, a first barrier/adhesion layer 414 isdeposited in the number of trenches 410 using a low energy ionimplantation. In one embodiment according to the teachings of thepresent invention, depositing the barrier/adhesion layer 414 includesdepositing a layer of zirconium 414 having a thickness of approximately5 to 100 Å. In alternate embodiments, depositing the barrier/adhesionlayer 414 includes depositing a barrier/adhesion layer 414 of titaniumand/or hafnium. In one embodiment, depositing the depositing a layer ofzirconium 414 includes depositing a layer of zirconium 414 having athickness of approximately 15 Å. This can be achieved using a 10¹⁷ ionimplant of zirconium. According to the teachings of the presentinvention, the layer of zirconium 414 is implanted at 100 electron volts(eV) into the surface of the trenches 410 in the polymer layer 408 usingan angle of implant normal to the wafer's surface as shown by arrows411. The structure is now as appears in FIG. 4C.

[0071] In FIG. 4D, a first seed layer 416 is deposited on the firstbarrier/adhesion layer 414 using a low energy ion implantation.According to the broader teachings of the present invention, depositingthe seed layer 416 on the barrier/adhesion layer 414 includes depositinga seed layer 416 selected from the group consisting of aluminum, copper,silver, and gold. However, according to the teachings of the presentembodiment, depositing the seed layer 416 includes depositing a layer ofcopper 416 having a thickness of approximately a 50 Å. This can beachieved using an 8×10¹⁶ ion implant of copper. According to theteachings of the present invention, using a low energy ion implantationincludes implanting the layer of copper 416 at 100 electron volts (eV)into the surface of the trenches 410 in the polymer layer. Also thelayer of copper 416 is implanted at an angle normal to the wafer'ssurface as shown by arrows 415. As one of ordinary skill in the art willunderstand upon reading this disclosure, implanting the layer of copper416 at an angle normal to the wafer's surface results in the seed layerof copper 416 remaining on a bottom surface 418 in the number oftrenches 410 and to a much lesser extent on the side surfaces 420 of thenumber of trenches 410. In one embodiment, an optional layer of aluminum421 is deposited over the copper seed layer 416 again using a low energyion implantation of 100 electron volts (eV). The optional layer ofaluminum 421 is deposited to have a thickness of approximately a 50 Å.This can be achieved using a 3×10¹⁶ ion implant of aluminum normal tothe wafer surface as shown by arrows 415. As one of ordinary skill inthe art will understand upon reading this disclosure, the layer ofaluminum 421 is used to protect the copper seed layer 416 from oxidationprior to subsequent processing steps. The structure is now as appears inFIG. 4D.

[0072]FIG. 4E illustrates the structure after the next sequence ofprocessing steps. As one of ordinary skill in the art will understandupon reading this disclosure, the residual photoresist layer 412 hasserved as a blocking layer to define the implant areas for thebarrier/adhesion layer 414, the seed layer 416, and the layer ofaluminum 421. The residual photoresist layer 412 is now removed using awet strip process, as the same will be understood by one of ordinaryskill in the art upon reading this disclosure. According to theteachings of the present invention, removing the residual photoresistlayer 412 includes removing the unwanted aluminum layer 421, theunwanted seed layer 416, and the unwanted barrier/adhesion layer 414from other areas of the wafer's surface, e.g. from over a number ofregions 413 outside of the trenches 410 on a top surface 419 of thefirst insulator layer 408. The structure is now as shown in FIG. 4E.

[0073] In FIG. 4F, a metallic conductor 420, or number of first levelmetal lines 420, is deposited over the seed layer 416 in the number oftrenches 410. According to teachings of the metallic conductor 420, ornumber of first level metal lines 420, is selected from the groupconsisting of aluminum, copper, silver, and gold depending on the typeof seed layer 416 which was deposited. According to this embodiment, anumber of copper metal lines 420, or first level copper metal lines 420are selectively formed on the copper seed layer 416. In one embodiment,the metallic conductor 420, or number of first level metal lines 420, isdeposited using a selective CVD process. In another embodiment,depositing a metallic conductor 420, or number of first level metallines 420, over the seed layer 416 includes depositing a metallicconductor 420 using electroless plating. Electroless copper plating isused to deposit sufficient copper to fill the number of trenches 410 tothe top surface 419 of the first insulator layer 408.

[0074] As shown in FIG. 4G, the process sequence may be continued toform any number of subsequent metal layers in a multilayer wiringstructure. FIG. 4G illustrates the structure after the next sequence ofprocessing steps. In FIG. 4G, a dual damascene process is used to defineand fill a first to a second level of vias and a second levelmetallurgy. To do so, a second polymer layer 424, or second layer ofpolyimide 424, is deposited over the wafer surface, e.g. the metallicconductor 420, or number of first level metal lines 420, and the firstpolymer layer 408. The second polymer layer 424 may similarly bedeposited using, for example, the process and material described inco-pending and commonly assigned application U.S. Ser. No. 09/128,859,entitled “Copper Metallurgy in Integrated Circuits,” which is herebyincorporated by reference. In one embodiment, depositing a secondpolymer layer 424 includes depositing a foamed second polymer layer 424.In one embodiment, the second polymer layer 424 is deposited and cured,forming a 10,000 Å thick second polymer layer 424 after curing. As oneof ordinary skill in the art will understand, upon reading thisdisclosure, other suitable thickness for the second polymer layer 424,or second insulator layer/material 424, may also be deposited as suitedfor forming a first to a second level of vias, e.g. second level vias,and a number of second level metal lines, the invention is not solimited. The second polymer layer 424, or second insulatorlayer/material 424 is patterned to define a second level of vias and anumber of second level metal lines in the second insulatorlayer/material 424 opening to the metallic conductor 420, or number offirst level metal lines 420. In other words, a second level of vias isdefined in a second mask layer of photoresist 426 and then the secondpolymer layer 424 is etched, using any suitable process, e.g. reactiveion etching (RIE), such that a second level of via openings 428 aredefined in the polyimide. Using the dual damascene process, a number ofsecond level metal lines are also defined in a second mask layer ofphotoresist 426 and the second polymer layer 424 is again etched, usingany suitable process, e.g. reactive ion etching (RIE), such that asecond level of metal line trenches 430 are defined in the polyimide.One of ordinary skill in the art will understand upon reading thisdisclosure, the manner in which a photoresist layer 426 can be mask,exposed, and developed using a dual damascene process to pattern asecond level of via openings 428 and a second level of metal linetrenches 430 in the second insulator layer/material 424.

[0075] As described previously, and according to the teachings of thepresent invention, a residual photoresist layer 426 is left in place onthe second insulator layer/material 424 in a number of regions 432outside of the second level of metal line trenches 430. A suitableplasma and/or wet cleaning process is used to remove any contaminatesfrom the second level of via openings 428 and a second level of metalline trenches 430, as the same will be understood by one of ordinaryskill in the art upon reading this disclosure. The structure is now asappears in FIG. 4G.

[0076]FIG. 4H illustrates the structure after the next sequence ofprocessing steps. In FIG. 4H, a second barrier/adhesion layer 434 isdeposited in the second level of via openings 428 and a second level ofmetal line trenches 430 using a low energy ion implantation. Asdescribed above, in one embodiment according to the teachings of thepresent invention, depositing the second barrier/adhesion layer 434includes depositing a layer of zirconium 434 having a thickness ofapproximately 5 to 100 Å. In alternate embodiments, depositing thesecond barrier/adhesion layer 434 includes depositing a barrier/adhesionlayer 434 of titanium and/or hafnium. In one embodiment, depositing thelayer of zirconium 434 includes depositing a layer of zirconium 434having a thickness of approximately 15 Å. In one embodiment, this isachieved using a 10¹⁷ ion implant of zirconium. According to theteachings of the present invention, the layer of zirconium 434 isimplanted at 100 electron volts (eV) into the surface of the secondlevel of via openings 428 and a second level of metal line trenches 430in the second polymer layer 424 using an implant angle normal to thewafer's surface as shown by arrows 425. The structure is now as appearsin FIG. 4H.

[0077]FIG. 4I illustrates the structure after the next sequence ofprocessing steps. In FIG. 4I, a second seed layer 436 is deposited onthe second barrier/adhesion layer 434 using a low energy ionimplantation. According to the broader teachings of the presentinvention, depositing the second seed layer 436 on the secondbarrier/adhesion layer 414 includes depositing a second seed layer 436selected from the group consisting of aluminum, copper, silver, andgold. However, according to the teachings of the present embodiment,depositing the second seed layer 436 includes depositing a second layerof copper 436 having a thickness of approximately a 50 Å. In oneembodiment, this is achieved using an 8×10¹⁶ ion implant of copper.According to the teachings of the present invention, using a low energyion implantation includes implanting the layer of copper 436 at 100electron volts (eV) into the second level of via openings 428 and thesecond level of metal line trenches 430 in the polymer layer. Also thelayer of copper 436 is implanted at an angle normal to the wafer'ssurface as shown by arrows 437. As one of ordinary skill in the art willunderstand upon reading this disclosure, implanting the layer of copper436 at an angle normal to the wafer's surface results in the second seedlayer of copper 436 remaining on a bottom surface 438 in the secondlevel of via openings 428 and to a much lesser extent on the sidesurfaces 440 of the second level of via openings 428 and a second levelof metal line trenches 430. In one embodiment, an optional layer ofaluminum 441 is deposited over the second copper seed layer 436 againusing a low energy ion implantation of 100 electron volts (eV). Theoptional layer of aluminum is deposited to have a thickness ofapproximately a 50 Å. In one embodiment, this is achieved using a 3×10¹⁶ion implant of aluminum normal to the wafer surface. As one of ordinaryskill in the art will understand upon reading this disclosure, the layerof aluminum 441 is used to protect the second copper seed layer 436 fromoxidation prior to subsequent processing steps. The structure is now asappears in FIG. 4I.

[0078]FIG. 4J illustrates the structure after the next sequence ofprocessing steps. As one of ordinary skill in the art will understandupon reading this disclosure, the residual photoresist layer 426 hasserved as a blocking layer to define the implant areas for the secondbarrier/adhesion layer 434, the second seed layer 436, and the aluminumlayer 441. The residual photoresist layer 426 is now removed using a wetstrip process, as the same will be understood by one of ordinary skillin the art upon reading this disclosure. According to the teachings ofthe present invention, removing the residual photoresist layer 426includes removing the unwanted aluminum layer 441, the unwanted seedlayer 436, and the unwanted barrier/adhesion layer 434 from other areasof the wafer's surface, e.g. from over a number of regions 432 outsideof second level of metal line trenches 430 on a top surface 442 of thesecond insulator layer 424. The structure is now as shown in FIG. 4J.

[0079] In FIG. 4K, a second metallic conductor 444, or second coreconductor 444, is deposited over or formed on the second seed layer 436and within the second barrier/adhesion layer 434 in the second level ofvia openings 428 and the second level of metal line trenches 430 in thepolymer layer. In this embodiment the second metallic conductor 444, orsecond core conductor 444, is copper, but in other embodiments of thepresent invention the second metallic conductor 444, or second coreconductor 444, can be selected from the group consisting of aluminum,silver, and gold. In one embodiment, the second metallic conductor 444,or second core conductor 444, is deposited using a selective CVDprocess. In another embodiment, depositing a second metallic conductor444, or second core conductor 444, over on the second seed layer 436 andwithin the second barrier/adhesion layer 434 includes depositing asecond metallic conductor 444, or second core conductor 444, usingelectroless plating. Electroless copper plating is used to depositsufficient copper to fill the second level of via openings 428 and thesecond level of metal line trenches 430 to the top surface 442 of thesecond insulator layer 424. Thus, the second barrier/adhesion layer 434,the second seed layer 436, and the second metallic conductor 444, orsecond core conductor 444, constitute a second number of conductivestructures which includes a number of second level vias and a number ofsecond level metal lines which are formed over and connect to a firstnumber of conductive structures, e.g. the metallic conductor 420, ornumber of first level metal lines 420.

[0080] As one of ordinary skill in the art will understand upon readingthis disclosure, the above described method embodiments can be repeateduntil the requisite number of metal layers are formed.

[0081]FIG. 4L illustrates the structure following the final sequence ofprocessing steps. Upon completion of the last level of metal, the entirepolymer structure, e.g. first polymer layer 408 and second polymer layer424, are removed using an O₂ plasma etch. The structure is now asappears in FIG. 4L.

[0082]FIG. 5, is an illustration of an embodiment of an integratedcircuit formed according to the teachings of the present invention. Asshown in FIG. 5, the integrated circuit includes a metal layer in anintegrated circuit. The metal layer includes a number of first levelvias 507A and 507B connecting to a number of silicon devices 501A and501B in a substrate 500. A number of first level metal lines 520 areformed above and connect to the number of first level vias 507A and507B. A barrier/adhesion layer 518 having a thickness in the range of 5to 150 Angstroms is formed on the number of first level metal lines 520.A seed layer 516 having a thickness in the range of 5 to 150 Angstromsis formed at least between a portion of the barrier/adhesion layer 518and the number of first level metal lines 520. As described above thebarrier adhesion layer 50 having a thickness in the range of 5 to 150Angstroms includes a barrier/adhesion layer selected from the groupconsisting of titanium, zirconium, and hafnium. In one embodiment, asshown in FIG. 5, the number of first level vias 507A and 507B connectingto a number of silicon devices 501A and 501B in substrate 500 aresurrounded by an insulator layer.

[0083] As described above the number of first level metal lines 502includes a number of first level metal lines 520 is selected from thegroup consisting of Aluminum, Copper, Silver, and Gold. In oneembodiment, the integrated circuit 503 comprises a portion of anintegrated memory circuit 503. In this embodiment, the number of silicondevices 501A and 501B includes one or more transistors 501A and 501B inthe substrate 500.

[0084] As one of ordinary skill in the art will understand upon readingthis disclosure, any one of the embodiments as shown in FIGS. 1K, 2K,3K, and/or 4L can comprise a portion of an integrated circuit accordingto the teachings of the present invention.

[0085]FIG. 6 illustrates an embodiment of a system 600 including aportion of an integrated circuit formed according to any of theembodiments described in the present application. As one of ordinaryskill in the art will understand upon reading this disclosure, thissystem 600 includes a processor 610 and an integrated circuit, orintegrated memory circuit 630 coupled to the processor 610. Theprocessor 610 can be coupled to the integrated memory circuit 630 viaany suitable bus, as the same are known and understood by one ofordinary skill in the art. In the embodiment, the processor 610 andintegrated circuit 630 are located on a single wafer or die. Again, atleast a portion of the integrated circuit 630 includes a portion of anintegrated circuit 603 as disclosed in the various embodiments providedherein.

CONCLUSION

[0086] Thus, structures and methods have been provided which improve theperformance of integrated circuits according to shrinking design rules.The structures and methods include a diffusion barrier and a seed layerin an integrated circuit both formed using a low energy ion implantationfollowed by a selective deposition of metal lines for the integratedcircuit. According to the teachings of the present invention, theselective deposition of the metal lines avoids the need for multiplechemical mechanical planarization (CMP) steps. The low energy ionimplantation of the present invention allows for the distinct placementof both the diffusion barrier and the seed layer. A residual resist canbe used to remove the diffusion barrier and the seed layer from unwantedareas on a wafer surface. The structures formed by the described novelprocesses accommodate aluminum, copper, gold, and silver metalinterconnects.

[0087] Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement which is calculated to achieve the same purpose maybe substituted for the specific embodiment shown. This application isintended to cover any adaptations or variations of the presentinvention. It is to be understood that the above description is intendedto be illustrative, and not restrictive. The scope of the inventionincludes any other applications in which the above structures andfabrication methods are used. The scope of the invention should bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed:
 1. A metal layer in an integrated circuit, comprising:a number of first level vias connecting to a number of silicon devicesin a substrate; and a number of first level metal lines formed above andconnecting to the number of first level vias; a barrier/adhesion layerhaving a thickness in the range of 5 to 150 Angstroms formed on thenumber of first level metal lines; and a seed layer having a thicknessin the range of 5 to 150 Angstroms formed at least between a portion ofthe barrier/adhesion layer and the number of first level metal lines. 2.The metal layer of claim 1, wherein the barrier/adhesion layer having athickness in the range of 5 to 150 Angstroms includes a barrier/adhesionlayer selected from the group consisting of titanium, zirconium, andhafnium.
 3. The metal layer of claim 1, wherein the number of firstlevel vias connecting to a number of silicon devices in a substrate aresurrounded by an insulator layer.
 4. The metal layer of claim 1, whereinthe barrier/adhesion layer formed on the number of first level metallines is surrounded by a polyimide insulator layer.
 5. The metal layerof claim 1, wherein the number of first level metal lines includes anumber of first level metal lines is selected from the group consistingof Aluminum, Copper, Silver, and Gold.
 6. An integrated memory circuit,comprising: a substrate including one or more transistors; an insulatorlayer overlying the substrate having one or more first level viasconnecting to the one or more transistors in the substrate; and apolyimide layer overlying the insulator layer including one or moreconductive structures formed above and connecting to the one or morefirst level vias, each of the one or more conductive structuresincluding: a number of first level metal lines; a barrier/adhesion layerhaving a thickness in the range of 5 to 150 Angstroms formed on thenumber of first level metal lines; and a seed layer having a thicknessin the range of 5 to 150 Angstroms formed at least between a portion ofthe barrier/adhesion layer and the number of first level metal lines. 7.A system, comprising: a processor; and an integrated memory circuitcoupled to the processor, wherein the integrated memory circuit furtherincludes: a substrate including one or more transistors; an insulatorlayer overlying the substrate having one or more first level viasconnecting to the one or more transistors in the substrate; and apolyimide layer overlying the insulator layer including one or moreconductive structures formed above and connecting to the one or morefirst level vias, each of the one or more conductive structuresincluding: a number of first level metal lines; a barrier/adhesion layerhaving a thickness in the range of 5 to 150 Angstroms formed on thenumber of-first level metal lines; and a seed layer having a thicknessin the range of 5 to 150 Angstroms formed at least between a portion ofthe barrier/adhesion layer and the number of first level metal lines. 8.The system of claim 7, wherein the barrier/adhesion layer having athickness in the range of 5 to 150 Angstroms includes a barrier/adhesionlayer selected from the group consisting of titanium, zirconium, andhafnium.
 9. The system of claim 7, wherein the a seed layer having athickness in the range of 5 to 150 Angstroms formed at least between aportion of the barrier/adhesion layer and the number of first levelmetal lines includes a copper seed layer, and the number of first levelmetal lines includes a number of copper metal lines.
 10. A metal layerin an integrated circuit, comprising: a number of first level vias in afirst insulator layer connecting to a number of silicon devices in asubstrate; and an oxide layer formed over the number of first level viasin the first insulator layer, wherein the oxide layer includes a numberof conductive structures connecting from a top surface of the oxidelayer to the number of first level vias, each conductive structure,comprising: a layer of Titanium or Zirconium having a thickness ofapproximately 50 Angstroms; a first layer of Aluminum on the layer ofTitanium or Zirconium having a thickness of approximately 50 Angstroms;a layer of Copper on the first layer of Aluminum having a thickness ofapproximately 10 Angstroms; and a second layer of Aluminum on the layerof Copper having a thickness of approximately 50 Angstroms.
 11. A metalinterconnect in an integrated circuit, comprising: a number of firstlevel vias in a first insulator layer connecting to a number of silicondevices in a substrate; and an oxide layer formed over the number offirst level vias in the first insulator layer, wherein the oxide layerincludes a number of conductive structures connecting from a top surfaceof the oxide layer to the number of first level vias, each conductivestructure, comprising: a layer of tantalum having a thickness ofapproximately 100 Angstroms; a layer of Nitrogen on the layer oftantalum; a seed layer of Copper on layer of Nitrogen having a thicknessof approximately 100 Angstroms; and a copper metal line formed on theseed layer of copper.
 12. The metal layer of claim 11, wherein eachconductive structure further includes a layer of tantalum nitrideforming a top surface of each conductive structure such that the topsurface of each conductive structure is level with the top surface ofthe oxide layer.
 13. A wiring structure in an integrated circuit,comprising: a number of first level vias in a first insulator layerconnecting to a number of silicon devices in a substrate; and a firstnumber of conductive structures formed over and connecting to the numberof first level vias in the first insulator layer, each conductivestructure, comprising: a layer of zirconium having a thickness ofapproximately 15 Angstroms; a seed layer of copper on the layer ofzirconium having a thickness of approximately 50 Angstroms; and a coppermetal line formed on the seed layer of copper.
 14. The wiring structureof claim 13, wherein each conductive structure further includes a layerof aluminum having a thickness of approximately 50 Angstroms formedbetween the seed layer of copper and the copper metal line.
 15. Thewiring structure of claim 13, wherein the wiring structure furtherincludes a polymer layer surrounding the number of conductivestructures.
 16. The wiring structure of claim 15, wherein the polymerlayer includes a foamed polymer layer.
 17. The wiring structure of claim13, wherein the wiring structure further includes: a second number ofconductive structures including a number of second level vias and anumber of second level metal lines formed above and connecting to thefirst number of conductive structures, wherein each of the second numberof conductive structures includes: a layer of zirconium having athickness of approximately 15 Angstroms; a seed layer of copper on atleast a portion of the layer of zirconium having a thickness ofapproximately 50 Angstroms; and a core copper conductor over the seedlayer and within the layer of zirconium.
 18. A multilayer wiringstructure in an integrated circuit assembly, comprising: a number offirst level vias in a first insulator layer connecting to a number ofsilicon devices in a substrate; a first number of conductive structuresformed over and connecting to the number of first level vias in thefirst insulator layer, each conductive structure, comprising: a firstbarrier/adhesion layer having a thickness in the range of 5 to 150Angstroms; a first seed layer formed on at least a portion of thebarrier/adhesion layer having a thickness in the range of 5 to 150Angstroms; and a first core conductor formed on the first seed layer andwithin the first barrier/adhesion layer; and a second number ofconductive structures includes a number of second level vias and anumber of second level metal lines, wherein the second number ofconductive structures are formed over and connect to the first number ofconductive structures, and wherein each of the second number ofconductive structures includes: a second barrier/adhesion layer having athickness in the range of 5 to 150 Angstroms; a second seed layer formedon at least a portion of the barrier/adhesion layer having a thicknessin the range of 5 to 150 Angstroms; and a second core conductor formedon the second seed layer and within the second barrier/adhesion layer.19. The multilayer wiring structure of claim 18, wherein the first andthe second number of conductors are surrounded by a polyimide layer. 20.The multilayer wiring structure of claim 18, wherein the polyimide layerincludes a foamed polyimide layer.
 21. The multilayer wiring structureof claim 18, wherein the first and the second barrier/adhesion layersinclude a first and a second barrier/adhesion layer selected from thegroup consisting of tantalum nitride, titanium, zirconium, and hafnium.22. The multilayer wiring structure of claim 18, wherein the first andthe second core conductors include a metal conductor selected from thegroup consisting of Aluminum, Copper, Silver, and Gold.
 23. Themultilayer wiring structure of claim 18, wherein the first and thesecond seed layers include a first and a second seed layer selected fromthe group consisting of Aluminum, Copper, Silver, and Gold.
 24. Theintegrated memory circuit of claim 6, wherein the insulator layerincludes Si₃N₄.
 25. The integrated memory circuit of claim 24, whereinthe Si₃N₄ has a thickness between about 100 Å to about 500 Å.
 26. Theintegrated memory circuit of claim 6, wherein the barrier/adhesion layerhaving a thickness in the range of 5 to 150 Angstroms includes abarrier/adhesion layer selected from the group consisting of titanium,zirconium, and hafnium.
 27. The integrated memory circuit of claim 6,wherein the seed layer having a thickness in the range of 5 to 150Angstroms formed at least between a portion of the barrier/adhesionlayer and the number of first level metal lines includes a copper seedlayer, and the number of first level metal lines includes a number ofcopper metal lines.
 28. The metal layer of claim 10, wherein theinsulator layer includes Si₃N₄ having a thickness between about 100 Å toabout 500 Å.
 29. The metal layer of claim 10, wherein the oxide layerincludes a fluorinated silicon oxide layer.
 30. An integrated circuit,comprising: a substrate including one or more transistors; an insulatorlayer overlying the substrate having one or more first level viasconnecting to the one or more transistors in the substrate; and apolyimide layer overlying the insulator layer including one or moreconductive structures formed above and connecting to the one or morefirst level vias, each of the one or more conductive structuresincluding: a number of first level metal lines; a barrier/adhesion layerhaving a thickness in the range of 5 to 150 Angstroms formed on thenumber of first level metal lines; and a seed layer having a thicknessin the range of 5 to 150 Angstroms formed at least between a portion ofthe barrier/adhesion layer and the number of first level metal lines.31. The integrated circuit of claim 30, wherein the insulator layerincludes Si₃N₄.
 32. The integrated circuit of claim 31, wherein theSi₃N₄ has a thickness between about 100 Å to about 500 Å.
 33. Theintegrated circuit of claim 30, wherein the barrier/adhesion layerhaving a thickness in the range of 5 to 150 Angstroms includes abarrier/adhesion layer selected from the group consisting of titanium,zirconium, and hafnium.
 34. The integrated circuit of claim 30, whereinthe seed layer having a thickness in the range of 5 to 150 Angstromsformed at least between a portion of the barrier/adhesion layer and thenumber of first level metal lines includes a copper seed layer, and thenumber of first level metal lines includes a number of copper metallines.
 35. An integrated circuit, comprising: a substrate including oneor more transistors; an insulator layer overlying the substrate havingone or more first level vias connecting to the one or more transistorsin the substrate; and an oxide layer overlying the insulator layerincluding one or more conductive structures formed above and connectingto the one or more first level vias, each of the one or more conductivestructures including: a layer of Titanium or Zirconium having athickness of approximately 50 Angstroms; a first layer of Aluminum onthe layer of Titanium or Zirconium having a thickness of approximately50 Angstroms; a layer of Copper on the first layer of Aluminum having athickness of approximately 10 Angstroms; and a second layer of Aluminumon the layer of Copper having a thickness of approximately 50 Angstroms.36. The integrated circuit of claim 35, wherein the insulator layerincludes Si₃N₄ having a thickness between about 100 Å to about 500 Å.37. The integrated circuit of claim 35, wherein the oxide layer includesa fluorinated silicon oxide layer.